This proposal requests partial support for the Twenty-Eighth Annual Symposium on Fundamental Cancer Research, to be held February 25-28, 1975, on the subject "Cellular Membranes and Tumor Cell Behavior." The M.D. Anderson Symposium was initiated in 1946 and has been held annually since 1949, to consider various scientific aspects of cancer. This symposium currently attracts from 900 to 1300 persons from the United States and several foreign countries. The papers presented during the symposium are published in a monograph. Each year the Bertner Foundation Award is conferred during this symposium in recognition of an outstanding contribution to some facet of cancer research. The central role of cellular membrane systems in the organization and control of many cellular and intercellular functions has become increasingly apparent. Furthermore, aberrations in one or more cellular membrane systems is a common feature of neoplastic cells. Accumulating evidence indicates that these membrane aberrations may be responsible for the pleomorphism, temporal variability, loss of growth control and altered social behavior which characterize neoplastic cells. The objective of the 28th Annual Symposium on Fundamental Cancer Research is to explore the experimental evidence which supports the involvement of membrane alterations in neoplasia and to evaluate the significance of these observations to the induction, progression and spread of cancer. Leading researchers, presenting a wide variety of scientific disciplines will be invited to present their findings and provided the opportunity to interchange ideas with other speakers and participants at the symposium. Opportunity will also be provided to evaluate the current status of this area of research and to assess its significance for development of new approaches to cancer therapy.